1. Technical Field of the Invention
This invention most generally relates to the apparatus and methods of catheterization and related treatments of the genito-urinary and gastro-intestinal passages of mammals.
More particularly, the invention relates to catheters, dilators, occluders and stents, and means of emplacement and application of the same to mammalian genito-urinary and gastro-intestinal passages.
2. Background Art
The background of this invention is bound up in the traditional "push to advance" methodology of catheter emplacement, which is characterized by external pressure on a stiff or thick-walled catheter to traverse a delicate, mucosal-lined passage. While the topic was extensively discussed in a prior pending application by this inventor, the following further remarks will provide additional context to aid in understanding the prior art and the problems associated with it, as well as the further disclosure and claims which follow.
As many men age, their prostates become enlarged and obstruct the flow of urine through the urethra. This condition is known as benign prostatic hyperplasia or BPH, and results in a partial or total inability to urinate. The most common surgical intervention for BPH, transurethral resection of the prostate, or TURP, has a lengthy recovery period of up to one year, and presents a high operative risk for complications such as sexual dysfunction. Up to 10% of those subjected to such surgery are left with mild to moderate stress incontinence.
Approximately 400,000 patients in the United States and approximately 500,000 patients internationally were diagnosed in 1994 with BPH or cancer-induced bladder outlet obstructions that were sufficiently severe to warrant TURP or alternative surgery, according to industry sources.
Because of the high costs, medical risks and quality of life compromises associated with TURP, new technologies have begun to challenge TURP's position as the standard treatment for severe BPH. Recently, the U.S. Food and Drug Administration approved two drugs, tera zosin hydrochloride and rinasteride, to treat BPH. These drugs generally do not improve symptoms for six to nine months after treatment begins, and are not without side effects.
Urethral strictures are often due to fibrous tissue growth resulting from reaction to catheters or cystoscopes or from injury, birth defects or disease, and are commonly treated by urethral dilation, catheterization or surgery. Men with urethral strictures also experience a limited ability to urinate, which may cause extreme discomfort and, if left untreated may cause complications that necessitate catheterization.
The standard catheterization means for hospitalized and bed ridden patients is the Foley Catheter. The Foley or indwelling urethral catheter is pushed into the bladder and retained by a water-filled balloon at the distal end. It drains urine continuously from the bladder via a connecting tube into a bag worn on the leg or hung on the bed. But difficulty in placement has always been inherent in this design. This is due to the traditional "push to advance" technology, which necessitates a stiff thick-walled catheter to traverse the delicate mucosal lined urethra.
Often the French (unit of measurement) size of the catheter is dictated by the need for stiffness to insert rather than the lumen size to pass urine. A 14 French or smaller Foley is rarely used because catheters of this size lack the column strength needed to push the full length of the urethra into the bladder. The larger French Foley catheters are painful to place, uncomfortable when indwelling, and require a highly skilled care provider to insert.
Dilation is accomplished by pushing successively larger urethral dilation tubes through the urethra to increase the size of the lumen, a procedure which is painful and traumatic to the patient. Of course, any catheterization of a restricted passageway is inherently a dilation process. Surgical treatment of strictures involves surgical risks as well as complications, including infection, bleeding and restenosis, which requires further treatment.
Approximately 50,000 patients in the United States were diagnosed with recurrent urethral strictures in 1994, according to industry sources. The inventor estimates that approximately 75,000 additional patients were diagnosed internationally.
Women suffer from urinary incontinence far more often than men and at an younger age primarily because of the stress associated with pregnancy and childbirth, the shorter length of the female urethra, and the absence of a prostate. The U.S. Department of Health and Human Services (HHS) estimates that the involuntary loss of urine affects approximately 10 million Americans of which 8.5 million are women. Seven million of these women are non-institutionalized, or community-dwelling.
For women between the ages of 15 and 64, the prevalence of urinary incontinence is estimated to range from 10 to 25 percent of the population. For non-institutionalized persons over the age of 60, the prevalence of urinary incontinence ranges from 15 to 30 percent, with the prevalence in women twice that of men.
The involuntary loss of urine can be caused by a variety of anatomical and physiological factors. The type and cause of urinary incontinence is important to how the condition is treated and managed. The two broad categories of urinary incontinence are urge and stress incontinence. Some people suffer from what is termed mixed incontinence or a combination of stress and urge incontinence
Urge incontinence is the involuntary loss of urine associated with an abrupt and strong desire to void. In most cases, urge incontinence is caused by involuntary detrusor (the smooth muscle in the wall of the bladder) contractions or over-activity. For many people, urge incontinence can be satisfactorily managed with pharmaceuticals.
The more frequently occurring stress incontinence is the involuntary loss of urine caused by movement or activity that increases abdominal pressure. The most common cause of stress incontinence is hypermobility or significant displacement of the urethra and bladder neck during exertion. A less frequent cause of stress incontinence is intrinsic urethral sphincter deficiency (ISD), a condition in which the sphincter is unable to generate enough resistance to retain urine in the bladder. Medical professionals have categorized stress incontinence into three types. They are:
Type I--slight amount of hypermobility. This is a mild form of incontinence: about 25% of stress incontinence are in the group. PA1 Type II--A severe condition of hypermobility that characterizes an estimated 60% of stress incontinence sufferers. PA1 Type III--Caused by ISD and often so severe that a patient will leak while standing still. This group constitutes about 15% of the stress incontinence population.
Occluders are used in some cases to control incontinence. Occluders of the prior art are constructed and applied with the same push-to-advance concept as catheters and dilators described above, with the same liabilities. The basic occluder is a bulb or plug on a shaft which is inserted within a passageway to stop or prevent the normal flow of materials through the passageway, or driven all the way into the bladder, for example, and allowed to seat as a plug at the neck of the urethra to prevent the flow of urine from the bladder.
Intermittent catheterization is mainly used by people who are incontinent due to a failure of the nerves that link the bladder and the brain. This is called neuropathic bladder, and may occur in a wide variety conditions which include spina bifida, multiple sclerosis, spinal injury, slipped disc and diabetes. Intermittent catheterization may also be utilized by people who cannot empty the bladder because the bladder muscle is weak and does not contract properly.
Conventional intermittent catheters are simple tubes with a drain port at the internal end that enters the bladder. These tubes are usually smaller in diameter and stiffer than an indwelling catheter of the same size. This stiffness can make traditional push-to-advance catheterization difficult in men because the urethra is long and has an acute bend within the prostate. When the external sphincter is reached with a conventional catheter the sphincter muscle will contract making passage difficult.
Dilators, occluders and catheters of the prior art share the 4000 year-old push-to-advance technology where an ever present problem exists in making them stiff enough for full penetration of the subject passage and yet flexible enough to make the turns without undue risk of trauma, pain or puncture to the wall of the passageway when being pushed in. Self-administration is inhibited by all of the short-comings of the present art, and further injury, infection and discomfort may result from the resulting improper self-care.
In some patients, an alternate apparatus and method used to maintain long term drainage of the bladder is the use of a suprapubic tube.
Suprapubic catheterization of the bladder is performed via transabdominal puncture which enters the body above the pubic arch and is directed into the bladder using ultrasound or fluoroscopy to guide the trocar introducer and suprapubic catheter. The needle introducer is then removed when proper catheter placement within the bladder is confirmed, leaving the drainage catheter in place.
Long term drainage may require the fixation of the catheter at the skin using standard adhesive based interface components to address mechanical fixation, inflection control, and skin compatibility.
The distal end of the catheter is commonly contained within the bladder by inflated balloon, winged-shaped tip configurations which expand within the bladder, or preshaped curved catheter tips which curl to their original J-shape when stiffening wire is removed from the catheter lumen.
A problem with this form of distal end emplacement is that it is only unidirectional; that is, it only resists the inadvertent pulling out of the tip of the catheter from the wall of the bladder, while allowing the catheter to freely pass further into the bladder, and back out up to the point of the containment structure. This continuing catheter motion in and out of the bladder may irritate tissue and cause infection or other difficulty at the bladder-catheter interface. Urine is especially irritating to most parts of the human body that are outside the urinary tract.